Digital imaging systems that include mechanically oriented cameras and sensors commonly include signal paths that extend along rotatable mechanical booms or mounting structures. Signal paths that extend across rotatable structures typically include a slip ring interface which include a rotating side and a stationary side. For each channel in a slip ring interface, a contact on the stationary side wipes on a conductive track on the rotating side or vice versa to provide electrical contact there between.
It is often desirable to replace older cameras and/or sensors of a digital imaging system with newer generations of cameras and sensors without replacing the mounting and orienting hardware of the system. The newer cameras and sensors generally provide more advanced features and higher resolution imagery and output much more data at much higher data rates than older cameras and sensors.
Mechanical contacts such as those used in a slip ring interface can degrade and become unreliable due to wear, mechanical interference, vibration, or thermal effects that can vary channel impedances across the slip ring interface. Some degradation and the resulting variations in channel impedance may be tolerable in older video systems where a relatively small amount of data is transported across a channel. However, in more modern high definition and ultra-high definition imaging systems, the much larger amount of data being transported across a slip ring interface may be corrupted by high or varying channel impedances.
High impedance spots on a channel of a slip ring interconnect can result in a dropped line of video or even a whole dropped frame, for example. Image noise such as dropped lines or frames may cause errors or inaccuracies in many downstream processes such as tracking algorithms which are configured to process continuous imagery.
Prior attempt to improve data integrity across slip interconnects have included performing cyclic redundancy checks (CRC) at the conclusion of each video line to determine if the video line includes bit errors. When bit errors are detected the previous video line is substituted in place of the line of video with the errors. Such passive techniques are generally inadequate to provide data integrity of high speed video data transported across a slip ring interconnect. The previously known passive techniques for improving data integrity across slip ring interconnects do not adequately support transporting high speed video data over degraded slip rings, slip rings that are bandwidth limited from data line to data line, or slip ring interconnects that are temporally changing while under extreme rotations or temperatures, for example.
Other attempts to mitigate data integrity problems at a slip ring interface include replacing the slip ring with another type of interconnect, such as a cable wrap. However, the other type of interconnects generally do not have the dynamic functionality of a true slip ring. For example, a cable wrap interconnect can only be rotated through some limited angular range, whereas a slip ring interconnect can be rotated through an unlimited angular range.
Another technique for transporting high speed video data over a degraded interconnect is to compress the video data so that it can be transported over fewer channels and/or at a lower data rate. However, it is often desirable to transport uncompressed video data because compressed data generally includes undesirable artifacts and many tracker algorithms are optimized to operate with uncompressed data. Moreover, when a frame of compressed video data is corrupted, more data is lost than would be if the frame had included uncompressed video data.